1. Field of the Invention
The present invention relates to an armature for fuel pumps and a manufacturing method thereof, and more particularly to an armature for fuel pumps and a manufacturing method thereof, in which a polymer coating film is formed on an armature core such that the armature has corrosion resistance to an alcohol fuel and to a highly corrosive fuel.
2. Description of the Prior Art
Fuels for automobiles are generally based on petroleum, but petroleum resources are influenced directly by oil shocks caused by a rapid increase resulting from resource exhaustion and external factors. Thus, in recent years, studies on the development of alternative fuels for automobiles have been continued.
Particularly, as environmental concerns increase, considering alternative fuels as a method for reducing exhaust gas emissions increases as well.
Among alternative fuels for automobiles there is alcohol fuel which is composed of a mixture of ethanol or methanol with gasoline.
The alcohol fuel is advantageous in that it can increase the output of automobiles due to the high heat efficiency of alcohol and can significantly reduce exhaust gas emissions compared to the use of petroleum. Also, due to the exhaustion of fossil fuels, the use of the alcohol fuel is expected to increase further.
Meanwhile, in systems such as automotive gasoline engines or diesel engines which are driven by liquid fuels, a fuel tank for storing the fuel is provided. In the fuel tank, a fuel pump module for forcedly supplying the fuel stored in the fuel tank to the engine is provided.
The fuel pump module includes a fuel pump for transferring the fuel into the engine, and a motor including an armature is provided therein.
The armature comprises a central shaft, a core which is stacked on the central shaft and serves to form an electric field, a commutator which is disposed at one end of the core while coming into contact with a brush and serves to supply an electric current, and a protective portion for protecting the core. An impeller is connected to the central shaft and is rotated by a repulsive force between the magnetic fields of permanent magnets disposed outside the armature, thereby transferring the fuel.
The core is generally formed of steel, and when an alcohol fuel is used as an automobile fuel, there is a problem in that the core corrodes faster than when a typical fuel (based on petroleum) is used.
In an attempt to prevent this problem, a method of plating the core of the armature with nickel or tin has been proposed. However, the method has problems in that surface washing should necessarily be carried out in order to increase the adhesion of the nickel or tin plating and in that the nickel or tin used can be introduced into the core gap to cause internal corrosion.
Also, in order to prevent the washing solution from flowing into the core gap, a gap blocking process should be carried out before the surface washing process, resulting in an increase in the production cost.
For these reasons, it is required to develop an armature which has corrosion resistance to an alcohol fuel and, at the same time, can be easily produced.